LeetCode in Kotlin
1457. Pseudo-Palindromic Paths in a Binary Tree
Medium
Given a binary tree where node values are digits from 1 to 9. A path in the binary tree is said to be pseudo-palindromic if at least one permutation of the node values in the path is a palindrome.
Return the number of pseudo-palindromic paths going from the root node to leaf nodes.
Example 1:
Input: root = [2,3,1,3,1,null,1]
Output: 2
Explanation: The figure above represents the given binary tree. There are three paths going from the root node to leaf nodes: the red path [2,3,3], the green path [2,1,1], and the path [2,3,1]. Among these paths only red path and green path are pseudo-palindromic paths since the red path [2,3,3] can be rearranged in [3,2,3] (palindrome) and the green path [2,1,1] can be rearranged in [1,2,1] (palindrome).
Example 2:
Input: root = [2,1,1,1,3,null,null,null,null,null,1]
Output: 1
Explanation: The figure above represents the given binary tree. There are three paths going from the root node to leaf nodes: the green path [2,1,1], the path [2,1,3,1], and the path [2,1]. Among these paths only the green path is pseudo-palindromic since [2,1,1] can be rearranged in [1,2,1] (palindrome).
Example 3:
Input: root = [9]
Output: 1
Constraints:
- The number of nodes in the tree is in the range
[1, 105]. 1 <= Node.val <= 9
Solution
import com_github_leetcode.TreeNode
/*
* Example:
* var ti = TreeNode(5)
* var v = ti.`val`
* Definition for a binary tree node.
* class TreeNode(var `val`: Int) {
* var left: TreeNode? = null
* var right: TreeNode? = null
* }
*/
class Solution {
private var ans = 0
private lateinit var arr: IntArray
fun pseudoPalindromicPaths(root: TreeNode?): Int {
ans = 0
arr = IntArray(10)
path(root)
return ans
}
private fun isPalidrome(): Int {
var c = 0
var s = 0
for (i in 0..9) {
s += arr[i]
if (arr[i] % 2 != 0) {
c++
}
}
if (s % 2 == 0) {
return if (c == 0) 1 else 0
}
return if (c <= 1) 1 else 0
}
private fun path(root: TreeNode?) {
if (root == null) {
return
}
if (root.left == null && root.right == null) {
arr[root.`val`]++
ans += isPalidrome()
arr[root.`val`]--
return
}
arr[root.`val`]++
path(root.left)
path(root.right)
arr[root.`val`]--
}
}